JP5521856B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire used in, for example, passenger cars, trucks, buses and the like.

  Generally, in this type of pneumatic tire, a plurality of sipes extending in the tire width direction are provided in the tread block, and the braking performance on wet road surfaces and snow / ice road surfaces is improved by the edge effect and drainage effect of the sipes. ing. In addition, since the rigidity of the block decreases when a sipe is provided, the sipe is formed into a waveform to form a three-dimensional shape, thereby suppressing the collapse of the block and increasing the rigidity of the block (for example, Patent Documents). 1).

JP 2008-143437 A

  By the way, when a snow clog occurs in the sipe on the road surface on the snow, the sipe is widened due to the snow clogging, and the width of the lug groove is reduced accordingly, and the braking performance is reduced due to the reduction of the snow column shear force. Particularly, the tire circumferential direction end portion of the block is less rigid than the tire circumferential direction center side, and the sipe is likely to open, so the sipe is likely to be clogged with snow. Also, if the sipe is moved from snowy road surface to icy road surface or wet road surface with snow clogging, the volume inside the sipe is reduced due to snow clogging, so the braking performance is reduced due to the reduced drainage effect. .

  Therefore, if a sipe with a small bent part that bends in a waveform is provided, the sipe can be prevented from opening more than a sipe with a large bent part, and snow clogging of the sipe can be reduced. If the bent portion is made small, the edge effect becomes insufficient, and there is a disadvantage that the braking performance is lowered. On the other hand, if a sipe having a large bent part is provided, a sufficient edge effect can be obtained. However, if the sipe bent part becomes large, the sipe is easily opened, and there is a drawback that snow clogging of the sipe increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a pneumatic tire that can reduce the snow clogging of the sipe and can sufficiently obtain the edge effect of the sipe. There is.

  In order to achieve the above object, the present invention provides a tread block having a plurality of sipes extending in the tire width direction at intervals in the tire circumferential direction while being bent in a wave shape so as to be uneven in the tire circumferential direction. In the pneumatic tire, the sipes having different bending portions are provided on one end side and the other end side of the block in the tire width direction, respectively, and the sipe having a small bending portion is provided outside the sipe having the large bending portion in the tire width direction. The sipe disposed on one end side and the other end side of the tire in the tire circumferential direction of the block is formed such that a sipe having a large bent portion is shorter in the tire width direction than the center side of the block in the tire circumferential direction. The sipe disposed on the center side in the tire circumferential direction is longer in the tire width direction than the one end side and the other end side in the tire circumferential direction of the block. It is formed to so that.

  As a result, a sipe with a small bent portion and a small sipe opening is disposed on the outer side in the tire width direction of the block that is likely to cause snow clogging, so that snow clogging of the sipe is reduced. In this case, the sipe on one end side and the other end side in the tire circumferential direction of the block is formed so that the sipe having a large bent portion is shorter in the tire width direction than the central side in the tire circumferential direction of the block. The sipe with a small sipe and a small sipe opening lengthens, and the sipe on the center side in the tire circumferential direction of the block is such that the sipe with a large bent portion is longer in the tire width direction than one end side and the other end side in the tire circumferential direction of the block. As a result, the sipe having a large bent portion and a large edge effect becomes long, and the snow clogging of the sipe is reduced and a sufficient edge effect is obtained in the entire block.

  According to the present invention, the snow clogging of the sipe can be reduced and a sufficient edge effect can be obtained, so that it is possible to suppress a decrease in braking performance on the snow road surface and the ice road surface. The tire performance can be improved.

Partial front sectional view of the pneumatic tire showing the first embodiment of the present invention Partial plan view of the tread Block perspective view Simplified schematic perspective view Partial plan view of block Block top view Schematic perspective view showing a modification of sipe Schematic perspective view showing another modification of Sipe Plan view showing a variation of the block The top view of the block which shows the 2nd Embodiment of this invention The top view of the block which shows the 3rd Embodiment of this invention The top view of the block which shows the 4th Embodiment of this invention Diagram showing test results

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 6. Note that the shading applied to the sipe in FIG. 4 is a shadow for clarifying the three-dimensional shape (the same applies to the modification of FIG. 11). Moreover, although the sipe is illustrated in a pseudo-planar shape, it is actually a narrow groove formed with a predetermined width.

  The pneumatic tire shown in the figure includes a tread portion 1 formed on the tire outer peripheral surface side, a pair of sidewall portions 2 formed on both sides in the tire width direction, and a pair of bead portions formed on both sides in the tire width direction. 3 and a shoulder portion 4 formed between the tread portion 1 and the sidewall portion 2.

  The pneumatic tire includes an inner liner 5 disposed on the inner surface of the tire, a carcass member 6 disposed on the outer side of the inner liner 5, a pair of bead members 7 disposed on both sides in the tire width direction, and the carcass member 6 The belt 8 is arranged on the outer side of the tire, the tread member 9 is arranged on the tire outer peripheral surface side, and the pair of sidewall members 10 are arranged on both tire side surfaces.

  The inner liner 5 is made of a sheet-like rubber having low gas permeability, and is disposed on the inner peripheral surface side of the carcass member 6.

  The carcass member 6 is formed by covering a plurality of reinforcing cords 6a with sheet-like rubber, and is folded back toward the sidewall portion 2 from the inner side to the outer side in the tire width direction so as to enclose the bead member at both ends.

  The bead member 7 includes a bead core 7a formed by bundling wires such as metal wires and a bead filler 7b formed of rubber having a substantially triangular cross section. The bead filler 7b is disposed on the outer peripheral side of the bead core 7a.

  The belt 8 is formed by coating a belt cord made of steel, high-strength fiber, or the like with a sheet-like rubber, and is disposed on the outer peripheral surface side of the carcass member 6.

  The tread member 9 is made of rubber formed by extrusion molding, and is disposed so as to cover the center side in the width direction of the carcass member 6 and the outer peripheral surface side of the belt 8.

  The sidewall member 10 is made of rubber formed by extrusion molding and is disposed so as to cover both sides of the carcass member 6 in the tire width direction.

  Further, the tread portion 1 is formed with a plurality of grooves 1a extending in the tire circumferential direction and the tire width direction, and a plurality of blocks 11 defined by the respective grooves 1a. Each block 11 is in the tire circumferential direction and the tire width direction. Is arranged. In this case, a plurality of first sipes 12 extending in the tire width direction are provided on one end side in the tire width direction of the block 11 (inner side in the vehicle width direction), and the other end side in the tire width direction of the block 11 (in the vehicle width direction). A plurality of second sipes 13 extending in the tire width direction are provided on the outer side.

  Each sipe 12, 13 is a narrow groove having a width of 0.4 mm to 1.5 mm, and one end in the length direction (tire width direction) penetrates the side surface of the block 11. Each sipe 12, 13 is bent into a waveform so as to be uneven in the tire circumferential direction, and is formed by a plurality of bent portions 12 a, 13 a having a linear waveform with respect to the length direction of the sipe 12. As shown in FIG. 4, each sipe 12, 13 has a three-dimensional shape in which the shapes of the bent portions 12a, 13a do not change along the depth direction of the sipe, that is, the same unevenness on one end side and the other end side in the depth direction. Are formed from a plurality of quadrangular surfaces.

  The bent portion 12a of the first sipe 12 is formed larger than the bent portion 13a of the second sipe 13, and the second sipe 13 is disposed on the outer side in the tire width direction with respect to the first sipe 12. . Further, the first and second sipes 12 and 13 arranged on one end side and the other end side in the tire circumferential direction of the block 11 are such that the first sipes 12 are shorter in the tire width direction than the second sipes 13. The first sipe 12 and the second sipe 12, 13 disposed on the center side in the tire circumferential direction of the block 11 are formed such that the first sipe 12 is longer in the tire width direction than the second sipe 13. Has been.

  In this case, as shown in FIG. 5, the size F1 of the bent portion 12a of the first sipe 12 in the tire circumferential direction is 1.3 times the size F2 of the bent portion 13a of the second sipe 13 in the tire circumferential direction. The size P1 of the bent portion 12a of the first sipe 12 in the tire width direction is 1.3 times less than the size P2 of the bent portion 13a of the second sipe 13 in the tire width direction. It is formed to be not less than twice and not more than 1.7 times.

  Further, as shown in FIG. 6, the length of the first sipe 12 in the tire width direction is W1, the length of the second sipe 13 in the tire width direction is W2, and the first and second adjacent to each other in the tire width direction. When the total length of the lengths W1 and W2 of the sipes 12 and 13 is W3, the length of the first sipes 12 (sipes located in the region A1 in FIG. 6) arranged closest to the end in the tire circumferential direction. W1 is 0.1 times to 0.3 times W3, and the length W1 of the first sipe 12 (sipe located in the region A3 in FIG. 6) closest to the center in the tire circumferential direction is 0. 4 times or more and 0.6 times or less, arranged between the first and second sipes 12, 13 closest to the end in the tire circumferential direction and the first and second sipes 12, 13 closest to the center in the tire circumferential direction The length W1 of the first sipe 12 (the sipe located in the region A2 in FIG. 6) is 0.2 times W3 or more 0 It is formed to be 5 times or less.

  According to the pneumatic tire of this embodiment, the braking performance on wet road surfaces and snow and ice road surfaces can be improved by the edge effect and drainage effect of the sipes 12 and 13. In this case, since the rigidity of the block 11 can be ensured by the bent portions 12a and 13a of the sipes 12 and 13, the block 11 can be prevented from falling down, and the uneven wear resistance and the steering stability can be improved. be able to.

  Further, in running on a snowy road surface, the lateral load is larger on the outer side than the inner side in the tire width direction of the block, and the sipe is likely to open to cause snow clogging. However, in this embodiment, the inner side of the block 11 in the tire width direction. Is provided with a first sipe 12 having a large bent portion 12a and a second sipe 13 having a small bent portion 13a provided on the outer side in the tire width direction of the block 11 so that snow clogging is likely to occur on the outer side in the tire width direction of the block 11. Since the second sipe 13 having a small sipe opening is arranged, snow clogging of the sipe 12, 13 can be reduced, and the deterioration of braking performance on the snowy road surface and on the ice road surface can be effectively suppressed. it can. In this case, since the second sipe 13 in which the sipe is difficult to open is disposed on the outer side in the tire width direction with a large lateral load, the rigidity on the outer side in the tire width direction of the block 11 can be increased more than on the inner side in the tire width direction. Can also be obtained.

  Further, the sipe is easy to open because the tire circumferential end portion side of the block is less rigid than the tire circumferential center side. However, the first sipe 12 having a large bent portion 12a on the tire circumferential end portion side of the block 11. Is formed so as to be shorter in the tire width direction than the first sipe 12 on the center side in the tire circumferential direction of the block 11 so that the second sipe 13 with less opening of the sipe becomes longer and the block 11 On the center side in the tire circumferential direction, the first sipe 12 having a large bent portion 12a is formed so as to be longer in the tire width direction than the first sipe 12 on the tire circumferential direction end side of the block 11, thereby forming an edge. Since the first sipe 12 having a large effect is lengthened, the snow clogging of the sipe 12, 13 can be reduced in the entire block 11. Moni, it is possible to obtain a sufficient edge effect.

  Further, if the size of the bent portion 12a of the first sipe 12 relative to the bent portion 13a of the second sipe 13 is too small, a sufficient edge effect cannot be obtained, and if too large, the sipe is likely to open. The size F1 of the bent portion 12a of the first sipe 12 in the tire circumferential direction is 1.3 times to 1.7 times the size F2 of the bent portion 13a of the second sipe 13 in the tire circumferential direction. The size P1 of the bent portion 12a of the first sipe 12 in the tire width direction is 1.3 times to 1.7 times the size P2 of the bent portion 13a of the second sipe 13 in the tire width direction. By forming so as to be, it is optimal for obtaining a sufficient edge effect with less snow clogging.

  Furthermore, if the length in the tire width direction of the first sipe 12 relative to the second sipe 13 is short on the tire circumferential direction end side and long on the tire circumferential direction center side, a sufficient edge effect is obtained with less snow clogging. Therefore, the first and second sipes 12 and 13 arranged closest to the end in the tire circumferential direction have the first and second lengths W1 of the first sipes 12 in the tire width direction. The first and second sipes 12, 13 are formed so as to be not less than 0.1 times and not more than 0.3 times the total length W3 of the sipes 12, 13, and are arranged closest to the center in the tire circumferential direction. The length W1 of the first sipe 12 in the tire width direction is 0.4 times or more and 0.6 times or less of the total length W3 of the first and second sipe 12, 13 and is the most tire circumference. The first and second sipes 12, 13 on the end side in the direction of the tire and the center side in the tire circumferential direction The first and second sipes 12 and 13 are arranged between the first and second sipes 12 and 13, and the length W1 of the first sipes 12 in the tire width direction is the first and second sipes. The length of the first and second sipes 12 and 13 in the tire width direction is set to be the tire of the block 11 by forming the total length W3 of 12 and 13 to be 0.2 to 0.5 times the total length W3. It can be optimized at any position in the circumferential direction.

  In the above embodiment, the sipe 12 and 13 are formed in a three-dimensional shape in which the shape of the bent portions 12a and 13a does not change along the depth direction of the sipe. Thus, by forming in the three-dimensional shape which changes along the depth direction of a sipe, the opening of the sipe 12 and 13 can be suppressed, and snow clogging can be reduced more. That is, the sipe 14 shown in the modified example of FIG. 7 is formed of a plurality of triangular surfaces so that the bent portion 14a has irregularities in opposite directions on one end side and the other end side in the depth direction. Further, the sipe 15 shown in another modified example of FIG. 8 is formed by a plurality of triangular surfaces so that the bent portion 15a is uneven in opposite directions on one end side and the other end side in the depth direction. It is formed in multiple steps in the vertical direction.

  In the above embodiment, the block 11 is formed in a rectangular shape. However, as shown in FIG. 9, the angle formed by the side 11a extending in the tire width direction and the side 11b extending in the tire circumferential direction is 40 ° or more 90 °. The block 11 can be formed in a parallelogram shape as long as it has a square shape of less than or equal to °.

  Further, in the above-described embodiment, the bent portions 12a and 13a bent so as to form a linear waveform with respect to the sipe depth direction are shown, but a bent portion bent so as to form a curved waveform is provided. It may be.

  FIG. 10 shows a second embodiment of the present invention, in which the sipe closest to the end in the tire circumferential direction of the block 11 is formed by only the second sipe 13 having a small bent portion 13a. Thereby, the snow clogging in the tire circumferential direction edge part side with low block rigidity can be suppressed more effectively.

  FIG. 11 shows a third embodiment of the present invention. The third sipe from the tire circumferential direction end portion side as well as the tire circumferential direction end portion side of the block 11 is a second bent portion 13a. It is formed only by the sipe 13. Thereby, the snow clogging in the whole block 11 can be suppressed more effectively.

  FIG. 12 shows a fourth embodiment of the present invention, in which the sipes 12 and 13 on the end side in the tire circumferential direction of the block 11 are not opened on the end surface of the block 11 in the tire width direction. It is formed up to slightly before the end. Thereby, even when the first and second sipes 12 and 13 having different sizes of the bent portions 12a and 13a are provided on the end portion side of the block 11 in the tire circumferential direction, the end portions in the tire circumferential direction having low block rigidity are provided. Snow clogging on the side can be more effectively suppressed.

  Here, for Examples 1 to 6 and Comparative Example of the present invention, tests on snow braking performance, ice braking performance and uneven wear resistance were performed, and the results shown in FIG. 13 were obtained. In addition, about the dimension and position of a sipe, the code | symbol of FIG.5 and FIG.6 is used.

  In Examples 1 to 6, a sipe having a large bent portion (first sipe) is provided on the inner side in the tire width direction of the block, and a sipe having a small bent portion (second sipe) is provided on the outer side in the tire width direction of the block. The sipe disposed on the tire circumferential direction end side of the block is formed so that the sipe having a large bent portion is shorter in the tire width direction than the sipe having a small bent portion, and disposed on the center side in the tire circumferential direction of the block. A sipe having a large bent portion was formed so that a sipe having a large bent portion was longer in the tire width direction than a sipe having a small bent portion. In this case, in Examples 2 and 3, the sipe on the inner side in the tire width direction is different from that in Example 1 in the size F1 in the tire circumferential direction and the size P1 in the tire width direction. The ratio W1 / W3 of the first sipe length W1 and the total length W3 of the first and second sipe located in the respective regions A1 to A3 in the tire circumferential direction is different from that of the first embodiment. . Further, in Examples 1 to 4 and Example 6, the sipe shown in FIG. 4 (a three-dimensional sipe in which the shape of the bent portion does not change along the depth direction of the sipe, hereinafter referred to as sipe shape A). In Example 5, the sipe shown in FIG. 8 (a three-dimensional sipe in which the shape of the bent portion changes along the depth direction of the sipe, hereinafter referred to as the sipe shape B) was further used. In Example 6, the sipe shown in FIG. 12 (the sipe in which the ends on the one end side and the other end side in the tire width direction are not opened on the end surface in the tire width direction of the block) was used.

  In the comparative example, a sipe having a large bent portion (first sipe) is provided on the inner side in the tire width direction of the block, and a sipe having a small bent portion (second sipe) is provided on the outer side in the tire width direction of the block. The inner and outer sipes were formed so that the length in the tire width direction was the same at any position in the tire circumferential direction of the block.

  In Examples 1 to 6 and Comparative Example, the height of the block is 10 mm, the width of the sipe is 0.4 mm, the depth of the sipe is 7.0 mm, and the distance c between the first sipe and the second sipe is A 0.5 mm one was used.

  In this test, a tire having a tire size of 215 / 60R16 and an air pressure of 230 kPa was mounted on a normal passenger car (rear wheel drive) having a displacement of 2000 cc.

  In the snow braking performance test, the reciprocal of the distance from the start of braking at a speed of 40 km / h to the stop of the vehicle on the road surface on snow was indexed, and Examples 1 to 6 were evaluated using the comparative example as 100. In this case, the larger the index value, the more superior.

  In the on-ice braking performance test, after performing the on-snow braking performance test, the reciprocal of the distance from the start of braking at a speed of 40 km / h to the stop of the vehicle on the road surface is indexed. 1-6 were evaluated. In this case, the larger the index value, the more superior.

  In the uneven wear resistance test, after running on a dry road surface for 10,000 km, the reciprocal of the evaluation result based on the appearance of the degree of uneven wear (heel and toe wear) in the tread part (heel and toe wear) after travel was indexed and compared. Examples 1-5 were evaluated with 100 as an example. In this case, the larger the index value, the more superior.

  As a result of the test, the results of Examples 1 to 6 were superior in braking performance on snow, braking performance on ice and uneven wear resistance compared to the comparative example.

  DESCRIPTION OF SYMBOLS 1 ... Tread part, 11 ... Block, 12 ... 1st sipe, 12a ... Bending part, 13 ... 2nd sipe, 13a ... Bending part, 14 ... Sipe, 14a ... Bending part, 15 ... Sipe, 15a ... Bending part .

Claims (7)

In a pneumatic tire in which a plurality of sipes extending in the tire width direction while being bent in a waveform so as to form irregularities in the tire circumferential direction are provided in the tread portion block at intervals in the tire circumferential direction,
Provided with sipes having different bending portions on one end side and the other end side in the tire width direction of the block,
While arranging a sipe with a small bent part on the outer side in the tire width direction with respect to a sipe with a large bent part,
The sipes disposed on the tire circumferential direction one end side and the other end side of the block are formed so that the sipe having a large bent portion is shorter in the tire width direction than the tire circumferential direction center side of the block,
A sipe disposed on the center side in the tire circumferential direction of the block is formed so that a sipe having a large bent portion is longer in the tire width direction than one end side and the other end side in the tire circumferential direction of the block. tire. The sipe having a large bent portion and the sipe having a small bent portion are arranged such that the size of the large bent portion in the tire circumferential direction is 1.3 times to 1.7 times the size of the small bent portion in the tire circumferential direction. The pneumatic tire according to claim 1, wherein the pneumatic tire is formed. The sipe having a large bent portion and the sipe having a small bent portion are arranged such that the size of the large bent portion in the tire width direction is 1.3 times to 1.7 times the size of the small bent portion in the tire width direction. The pneumatic tire according to claim 1 or 2, wherein the pneumatic tire is formed. The sipe arranged at the end in the tire circumferential direction of the block has a total length in the tire width direction of a sipe having a large bend and a sipe having a large bend and a sipe having a large bend. While forming to be 0.1 times or more and 0.3 times or less,
The sipe disposed closest to the center in the tire circumferential direction of the block has a sipe having a large bend in the tire width direction of a sipe having a large bend and a sipe having a large bend and a sipe having a small bend. It is formed to be 4 times or more and 0.6 times or less,
A sipe that is arranged between the sipe that is closest to the tire circumferential end of the block and the sipe that is closest to the center of the tire in the tire circumferential direction. The pneumatic tire according to claim 1, 2 or 3, wherein the pneumatic tire is formed so as to be 0.2 times or more and 0.5 times or less the total length of the sipe having a small bent portion in the tire width direction. The sipe disposed closest to the end in the tire circumferential direction of the sipe is formed such that ends on one end side and the other end side in the tire width direction do not open to an end surface in the tire width direction of the block. Item 5. The pneumatic tire according to item 1, 2, 3 or 4. The pneumatic tire according to claim 1, 2, 3, 4, or 5, wherein the sipe is formed in a three-dimensional shape in which a shape of a bent portion changes along a depth direction of the sipe. The block is formed in a square shape in which an angle formed between a side extending in the tire width direction and a side extending in the tire circumferential direction is 40 ° or more and 90 ° or less. 6. The pneumatic tire according to 6.

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